What is CVE-2025-20340?

CVE-2025-20340 is a high-severity vulnerability in Cisco Ios Xr Software, classified under Uncontrolled Resource Consumption. CVSS score: 7.4/10. Published 2025-09-10.

How severe is CVE-2025-20340?

High severity. CVSS v3 base score is 7.4 out of 10.

Is CVE-2025-20340 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Resource exhaustion in Cisco Ios Xr Software

CVE-2025-20340

A vulnerability in the Address Resolution Protocol (ARP) implementation of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to trigger a broadcast storm, leading to a denial of service (DoS) condition on an affected…

Vulnerability class: DoS (Denial of Service)

EPSS: 0.006 (43.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.

Affected products

Cisco Ios Xr Software — versions 6.5.3, 6.5.29, 6.5.1

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

psirt@cisco.com

Frequently asked questions

What is CVE-2025-20340?: CVE-2025-20340 is a high-severity vulnerability in Cisco Ios Xr Software, classified under Uncontrolled Resource Consumption. CVSS score: 7.4/10. Published 2025-09-10.
How severe is CVE-2025-20340?: High severity. CVSS v3 base score is 7.4 out of 10.
Is CVE-2025-20340 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.